The disease state of stenotic tenosynovitis (hereinafter also referred to as “trigger finger”) is as follows: “A1 pulley,” which is a ligamentous tendon sheath (hereinafter referred to as “tendon sheath”) existing on the side of a matacarpophalangeal (MP) joint, which is a joint at the finger base, is thickened and finger flexor tendon (hereinafter referred to as “tendon”) strangulation occurs, and thereby sliding of the tendon and tendon sheath is prevented and bending and stretching of the finger become difficult so as to cause pain.
To conduct surgical treatment, an A1 pulley that has been thickened is incised for improved tendon sliding in the major axis direction to release strangulation of the tendon. The release of the strangulation often leads to quick improvement in bending and stretching and reliving the pain.
In the conventional surgery for a trigger finger, the palm skin is incised approximately 2 cm. In general, while directly looking at the tendon and tendon sheath, open tendon sheath incision surgery is performed to incise the A1 pulley. Problems involved with this generally conducted surgery method include post-surgical symptoms, such as pain due to scarring of a tissue in the incised skin area, difficulty in clenching fingers, and restrictions of hand movement in daily life until a stitch is removed.
Dupuytren's contracture is a serious disorder in bending and stretching of a finger since a palm aponeurotic membrane under the skin of the palm and finger (hereinafter referred to as “aponeurotic membrane”) is thickened and contracted, and the aponeurotic membrane is abnormally indurated and shortened.
The common surgery method for Dupuytren's contracture is aponeurectomy in which a substantial area of the palm and finger is incised to excise an abnormal aponeurotic membrane. In this method, however, the level of invasion is high, and there are problems such as the skill required for surgery and wound healing of the incised skin area.
As a measure for improving a relatively large incised skin area due to trigger finger surgery, a method called percutaneous surgery is used. In this method, minor skin incision of several millimeters is conducted, a dedicated surgical instrument, a single-use injection needle, or the like is inserted to blindly Incise an A1 pulley.
Also, for Dupuytren's contracture, there is another method called needle aponeurotomy that causes little invasion. To improve a finger bending and stretching disorder, this method is performed by blindly incising an abnormally indurated aponeurotic membrane under the skin using, e.g., a single-use syringe needle that has been pierced, from the palm. However, these types of surgery methods by blind operation involve a relatively high risk of injuring, by the needle, a tissue of a finger nerve, blood vessel, tendon, or the like.
A surgical instrument for use in the conventionally performed percutaneous tendon sheath incision surgery will now be described with reference to FIG. 11.
The tendon sheath incision blade shown in Patent Literature 1 can be used in both open surgery and percutaneous surgery. The tendon sheath incision blade includes a grip 101, a shaft 102 equipped on the grip, a blade portion 103 disposed on the side surface of the tip end portion of the shaft 102, and a guide portion 104 that extends in the direction from the lower section of the blade portion to the section toward which the blade portion protrudes. The blade disposed at the pointed end of the blade portion 103 is formed to have a circular arc shape in the area between the upper surface of the guide portion 104 and the upward inclining section of the blade portion 103. The sections above this circular arc-shaped upward inclining section of the blade, i.e., the middle and upper sections of the blade, are formed in a straight line so as to be in substantially parallel with the axial line direction of the shaft 102. The upper section of the blade portion 103 is formed in a step shape where the upper section protrudes from the side surface of the shaft 102.
This tendon sheath incision blade is inserted into the skin to incise the tendon sheath. When this tendon sheath incision blade is used in percutaneous surgery, the location of the tendon sheath cannot be confirmed directly and visually, and an incision blade without a blade portion to search for the entrance of the tendon sheath is prepared. After the entrance of the tendon sheath is searched for and the incision blade is in turn switched to one with a blade portion, an incision needs to be performed.
Another surgical instrument for use in percutaneous tendon sheath incision surgery will be described with reference to FIG. 12. The incision blade shown in Patent Literature 1, the tip end of a blade portion 105 to be inserted into the skin is thin, and has a special knife blade portion configured to incise a tendon so that the level of invention is low. A surgeon holding a handle portion 106 uses the surgeon's own sensation of hand and experience to blindly incise the tendon sheath. The surgeon thus needs to be practiced in use of the aforementioned incision blade.